1. Field of the Invention
This invention relates to a work table and, in particular, to a rotary work table for bonding of printing dies to flexible sheet material carrier.
2. Brief Statement of the Prior Art
High speed printing machines such as are used for the printing of cardboard boxes and the like have rotary mandrels on which the printing dies are mounted with a flexible sheet material (make-ready) as a carrier. The printing dies are molded rubber mats approximately one quarter to three sixteenths inch in thickness and are bonded to the flexible sheet which is typically of vinyl plastic, approximately 30 mils in thickness for mounting in the printing machine.
Heretofore, the flexible carrier sheets (make-ready), are placed on a flat work table, the location of the printing dies on the make-ready are plotted and the flat, rubber printing dies are bonded or cemented to the make-ready sheet while the latter is in a flat position on the work table.
The bonding of the printing dies to the make-ready sheet while the latter is on a flat table often causes difficulties in mounting of the make-ready to the rotary drum of the printing machine since the laminated assembly lacks adequate flexibility, often resulting in inadequately bonded edges of the printing dies which release from the make-ready sheet and extend above the cylindrical plane of the printing drum a sufficient distance that they transfer ink to the printed, flat work piece. This tendency becomes more pronounced with age and use of the printing dies since the make-ready and printing die assembly often tends to curl during storage in an opposite direction from its curvature when mounted on the printing drum.
While some attempts have been made to bond printing dies to make-ready sheets while supporting the sheets on a cylindrical work support, this approach has not been widely accepted since there is no single standard or fixed diameter for a printing drum and, consequently, the make-ready and printing die assembly must often assume curvatures of widely varied radii.